1. Field of the Invention
Aspects of the present invention relate to a subscriber identity module card and a terminal device having the same.
2. Description of the Related Art
A subscriber identity module (SIM) card is inserted to a portable terminal device (such as a cellular telephone, a personal digital assistant (PDA), a notebook computer, etc.) that is provided with a communicating function. The SIM card is a specific card of a global system for mobile communication (GSM) performing an interface function between the terminal device and a network. Furthermore, the SIM card includes various types of information about a user, such as a unique number, an account number, a registered telephone number, personal certification information, etc. If the user turns on the terminal device after mounting the SIM card to the terminal device, the terminal device communicates with the network using the information included in the SIM card, whereby the user is capable of using only a terminal device approved by the network.
For preventing an unfair using or malfunction of the SIM card, the terminal device determines in real time whether the SIM card is mounted. In general, the terminal device includes an SIM card connector to which the SIM card is connected, an SIM interface to communicate with the SIM card, and a switch to detect whether the SIM card is physically connected to the SIM connector. If the SIM card is inserted into the SIM connector, the switch is turned on so that electric information about the insertion of the SIM card is supplied to the SIM interface. Accordingly, the SIM interface can determine whether the SIM card is mounted.
Another method to determine whether the SIM card is mounted includes checking at predetermined time intervals whether the SIM card is mounted. Although this method has a superior reliability because this method directly checks whether the SIM card is mounted, determining by time intervals whether the SIM card is mounted interferes with a normal operation of the SIM card.